Relationships between Dental Roots and Surrounding Tissues for Orthodontic Miniscrew Installation

Abstract

Objective: To elucidate relationships between the dental roots and surrounding tissues in order to prevent complications after placement of a miniscrew. Materials and Methods: Twenty human mandibles and maxillas were used for this study. In the 200 sections of each mandible and maxilla, nine items were measured to investigate the relationships between the dental roots. Results: The interroot distance increased from anterior to posterior teeth and from the cervical line to the root apex in both the maxilla and the mandible. In the maxilla, the greatest interroot distance was between the second premolar and the first molar. In the mandible, the greatest interroot distance was between the first and second molars. The maxillary buccolingual bone width exceeded 10 mm from 7 mm (between canine and first premolar), 5 mm (between second premolar and first molar), and 4 mm (between first and second molars) above the cervical line. The mandibular buccolingual bone width exceeded 10 mm from 7 mm (between second premolar and first molar) and 4 mm (between first and second molars) below the cervical line. Conclusions:The safest zone for placement of a miniscrew in the maxilla was between the second premolar and the first molar, from 6 to 8 mm from the cervical line. The safest zone for placement of a miniscrew in the mandible was between the first and second molars, less than 5 mm from the cervical line. (Angle Orthod. 2009;79:37-45.)

Optimal sites for orthodontic mini-implant placement assessed by cone beam computed tomography

“…In the posterior region of the maxilla and the mandible the most suitable sites are between the second premolar and the first molar and between the first and second molars, which was also recommended in previous studies. 8,12,18 In the present study, males had a significantly thicker buccolingual dimension and buccal cortical thickness than females in both the maxilla and the mandible. Kim et al 22 found no statistical difference between sexes in the interradicular measurements of the posterior maxilla, probably because of the small sample size (35 patients).…”

“…The availability of a relatively large number of CBCT images for this study allowed the researchers to overcome the shortcoming of limited sample size in several previous studies. 11,12,18 Most studies on this topic have aimed to determine the safest sites for mini-screw placement by focusing on the posterior region of the jaws. [8][9][10][11] The fact, however, that mini-implants are often useful in the anterior region for space closure 4 or correction of overbite problems 6 necessitated the evaluation of the anterior region as well.…”

“…The means of the different measurements in this study were found to be in agreement with those obtained in other similar studies. 8,11,12,18 Limited data are available in the literature describing the buccal cortical thickness. The results of this study showed that in the maxilla the buccal cortical thickness had a certain pattern: the thickness increased as the cuts moved apically from the CEJ to the 4-mm level, and then they decreased again at the 6-mm level.…”

Effects of mandibular incisor intrusion obtained using a conventional utility arch vs bone anchorage

“…The probable reason for these failures may be the operator's ease (or difficulty) of placement on one side. Schnelle et al 18 and Hu et al 21 advised placement of implants of the smallest diameter and length in these risky areas in order to achieve stability. In this study, if higher force levels were used, the success rate might have been different.…”

“…Vertical movement of the center of resistance was 1.9 mm in the implant group and 1.4 mm in the utility arch group. Several studies [21][22][23][24] have found various amounts of lower incisor intrusion (1.02-3 mm) with conventional mechanics. In these studies protrusion of the lower incisors followed intrusion.…”